1. Field of the Invention
The present invention relates to lift and hoist mechanisms, more particularly, to a lift assembly that can be employed for raising and lowering a batten in theatrical and staging environments, wherein the lift assembly is a modular self contained unit that can be readily and securely installed in a wide variety of building configurations.
2. Description of Related Art
Performance venues such as theaters, arenas, concert halls, auditoriums, schools, clubs, convention centers and television studios employ battens or trusses to suspend lighting, scenery, drapery and other equipment which is moved relative to a stage or floor. These battens usually include pipe or joined pipe sections that form a desired length of the batten. The battens can be fifty feet or more in length. To support heavy loads, or where suspension points are spaced fifteen to thirty feet apart, the battens may be fabricated in either ladder, triangular or box truss configurations.
Battens often need to be lowered for exchanging and servicing the suspended equipment. To reduce the power necessary to raise and lower the battens, the battens are often counterweighted. The counterweights reduce the effective weight of the battens and any associated loads.
A number of elevating or hoisting systems are available for supporting, raising and lowering battens. One of the most common and least expensive batten elevating systems is a counterweighted carriage that includes a moveable counterweight for counterbalancing the batten and equipment supported on the batten.
Another common elevating or hoisting system employs a winch to raise or lower the battens. The winch may be either hand or electrically operated. Occasionally in expensive operations, a motorized winch or hydraulic or pneumatic cylinder device is used to raise and lower the batten.
More recently, modular lift assemblies have been employed to raise and lower battens. An example of such a conventional assembly is shown in FIGS. 1A-1C.
In the conventional lift assembly 1, a motor 4 is disposed in communication with a drum 6 such that the motor 4 rotates the drum 6. One or more wire cables 8 are wound around the drum 6 such that as the drum 6 rotates, the cables 8 are selectively wound about, or advanced from, the drum 6. A plurality of pulleys 10 is disposed to reroute and redirect the cables 8 as they are extended from the drum 6. In this manner, cables 8 extend generally horizontally from the lift assembly 1 before being rerouted vertically to attachment points on a batten 12 to be raised or lowered. The lift assembly preferably also includes a frame 14 that houses the drum 6 and motor 4, as well as other components comprising the lift assembly. The frame 14 is preferably mountable to I-beams (or similar support structures) 16 native to the arena in which the lift assembly 1 is to be used.
Such conventional lift assemblies 1 have revolutionized the way in which battens are raised and lowered. However, because the frame 14 is normally suspended from I-beams or other support structures, the frame is required to withstand a vertical load caused by the weight of the assembly and the weight of the object to be raised or lowered. Moreover, when the wire cables 8 are lead horizontally from the lift assembly and then dropped vertically to the batten 12, the assembly is also subject to a horizontal load. The vertical and horizontal loads may result in sagging or drooping at positions furthest from the support structures and relative bending with respect to the support structure 16 nearest the end of the lift assembly from which the cables 8 extend. These loads are further exacerbated when the weight of the battens is increased and when the distance between points at which the lift assembly is attached to the support structure is increased.
Such loads may result in deformations of the lift assembly, which may maliciously affect components of the lift assembly. For example, a shaft (not shown) driven by the motor 4 to rotate the drums 6 about which the cables 8 are wound may be up to seven feet in length, and even slight bending thereof may cause misalignment of the shaft with respect to bearings (not shown) in which the shaft rotates. As a result, a wobble of the rotating components with respect to each other is created, potentially shortening the life of the bearings, shaft, and/or drums, and increasing noise created by the lift assembly.
Thus, there is a need in the art for an improvement to existing modular lift assemblies, which improvement provides increased stiffness of the lift assembly to increase the life and efficiency of the assembly.
There is also a need in the art for an improvement to existing modular lift assemblies, which improvement provides for secured attachment of the modular lift assembly to existing structures within an environment.